The invention relates to rotary combustion engine of trochoid design. It includes a housing composed of a jacket having a multi-curved inner jacket face and two parallel side walls and a substantially horizontally disposed eccentric shaft which extends through circular apertures in the side walls. A liquid cooled piston is rotatably mounted on the eccentric. Oil control rings are mounted on the piston end walls which coact with the sidewalls of the side walls. A disk is provided in at least one piston end wall, said disk rotates with the eccentric shaft concentrically with respect to the rotational axis of the piston and has a hub which extends into the aperture of the adjacent side wall. The hub and the disks are provided with sealing rings in tight sealing engagement with the piston end wall and the wall of the aperture, respectively. The sealing rings encompass an annular chamber which is limited radially outwardly by the oil control rings. Such a rotary combustion engine is described in German Pat. No. 14 51 809, for example.
In this known rotary combustion engine the sealing ring which is mounted between the disk and the piston end wall prevents overflowing of cooling or lubricating liquids from the piston into the working chamber. In order to bring the sealing rings, which are inserted in grooves, into sealing engagement and thereby sealing the liquid cooled piston to the outside, a so-called intermediary sealing pressure is generated within the annular chamber. This intermediary sealing pressure is created under the influence of pressure gas which enters into the annular chamber from the working chamber through the oil control rings during operation of the combustion engine. However, since the sealing ring cooperating with the piston end wall reliably seals only at the presence of the intermediary sealing pressure, cooling fluid may flow from the piston over the sealing ring into the annular chamber when the combustion engine is not in operation. It had been shown that the cooling or lubricating liquid which penetrates into the annular chamber remains therein when the combustion engine is again operated and therefore flows into the working chamber through the oil sealing rings, and uselessly combusts therein.